1. Field of Invention
The present invention relates to a method of forming a thin-film, an apparatus to form a thin-film, a method of manufacturing a semiconductor device, an electro-optical unit, and an electronic apparatus.
2. Description of Related Art
In the related art, in general, semiconductor devices used for various electronic apparatuses include layers, such as semiconductor layers, insulating layers, and conductive layers. A CVD (Chemical Vapor Deposition) process or a sputtering process is principally used to form such insulating layers and conductive layers. A thermal CVD process, a plasma-CVD process, a photo-CVD process, or the like using a monosilane gas or a disilane gas is used to form a silicon layer, which is one of such semiconductor layers.
In the related art CVD and sputtering processes, there is a problem in that an apparatus to form a thin-film is expensive and large because a high-precision vacuum unit and a power-supply unit to generate plasma and so on are necessary. In order to address or solve the above problem, other related art methods, which are different from the above related art methods of forming the thin-films, can be used.
For example, the related art includes a method of forming a desired thin-film by applying a liquid material onto a substrate to form a coating and then heat-treating the coating. The thin-film forming method includes: applying the liquid material onto a surface of the substrate, and heat-treating the coated surface. According to this method, thin-films can be formed with an inexpensive compact apparatus at high productivity and low cost, thereby manufacturing thin-film devices at low cost.
In the applying step, a coating process, such as a spin-coating process or a droplet-ejecting process (a so-called inkjet process) is usually used. The related art includes the following exemplary device, apparatus, etc., for the spin-coating process: a spinner having a cover that can be readily detached when a treating solution is changed (see, for example, Japanese Unexamined Patent Application Publication No. 5-154430), a coating apparatus in which coating liquid can be applied onto a treating substrate while a cover of a rotating container is closed (see, for example, Japanese Unexamined Patent Application Publication No. 8-83762), and so on. For the inkjet process, the related art includes the following apparatus, etc.: an apparatus to form a uniform coating on a treating substrate in such a manner that the treating substrate and an inkjet head are rotated relative to each other while the angular speed and the moving speed are controlled, the inkjet head moves between a region close to the axis of rotation and a region far from the axis, and liquid is ejected from micro-nozzles of the inkjet head toward the treating substrate (see, for example, Japanese Unexamined Patent Application Publication No. 9-10657) and so on.
For the heat-treating, the related art includes the following process, etc.: a process of firing an insulating coating in a firing furnace in which the oxygen content is adjusted to a certain value or less (see, for example, Japanese Unexamined Patent Application Publication No. 9-213693) and so on. Furthermore, for the sequential steps including the applying and the heat-treating, for example, the related art includes the following method of forming a coating: coating liquid is dropped on a surface of a treating material; the resulting coating liquid is uniformly spread over the treating material surface; the resulting treating material, in which a part of the coating liquid for forming a coating is disposed at the periphery of the lower surface of the treating material, is transported to a vacuum drying apparatus; the treating material is dried to a certain degree; and the resulting treating material is then heated and dried (see, for example, Japanese Unexamined Patent Application Publication No. 11-262720).